From patchwork Fri May 8 18:15:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luke Nelson X-Patchwork-Id: 11537331 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B1B8215AB for ; Fri, 8 May 2020 18:16:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 754B3208CA for ; Fri, 8 May 2020 18:16:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="GVqt5wFx"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=cs.washington.edu header.i=@cs.washington.edu header.b="I6sVrCye" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 754B3208CA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=cs.washington.edu Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=i7UHSARk1d3c6M8ZM2pCrUDgJ9/s+ic0q9ZotJ03UhA=; b=GVqt5wFxOpqr69mnvrN5X2UM31 vnRdNoEIFkc8Urz5KAK9IaD7DSiueFfqOZF9gpc3kPywCRxvszAX+OoFeNMZQYWMWr+r5oPNGWnWZ RbgGln8CoUXCv3lVL/IE7CWZeJb2D0N0JM2qbBpWxoLDE8SObS4mrvO6ReB/p6kIN/ZrtrBN+KSzu hLci8WtX2ecPFkJOOWn8fVjHh5kcfLJXlHuICxicrXId19DbSxrHE7gxDAViaW4AzCwNX84VWhpwL SYOg6dV7oobZyH7nl6oZXQef7k5gP+kmpGFZ/RM4/yUu8pPKkY2JKoH2KrCxTC0hqwLls0Gc2cn+0 IqJM/3kQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jX7Xf-0007qJ-00; Fri, 08 May 2020 18:16:11 +0000 Received: from mail-pl1-x643.google.com ([2607:f8b0:4864:20::643]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jX7XV-0007gC-Pw for linux-arm-kernel@lists.infradead.org; Fri, 08 May 2020 18:16:03 +0000 Received: by mail-pl1-x643.google.com with SMTP id b8so1078129plm.11 for ; Fri, 08 May 2020 11:16:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cs.washington.edu; s=goo201206; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=+grFk/1b6m5GXQB6Do7/JZsbw7ECp6r+S8upQGe4+gI=; b=I6sVrCyeN1Al9+YXglL0XwffqWho/yTDT1r7S/K6Apz4jUPalQFiMfGpHSI54ALlc+ V6dIZM6i+WLjQlh5ywJ5byFfTeg9EfIH49M7i84H/uOfLRN+vZzIfo59Q3OEXEIJQEsx 7x2tnn1OPyog3FsuhfzlEBVIKdmsUugJfu5W4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=+grFk/1b6m5GXQB6Do7/JZsbw7ECp6r+S8upQGe4+gI=; b=lZK6PkBWITs8BZ4i/RcIf9jmtOaqvyOaFqV2xdjxCfwfWR6KoDV2SEPzU2Kk/N0OHE hRezwXtMmOC9ieizWdVfdNJPy2Oa8dsY8cNqrqt5ftoyb/Iakj7kRJLkGCHN0TWgkj6g /1htIRVaP/SNe1GOH0vkGkNYDRj4nS6PYQgvBF7WksL4m7H+M8MhOqW1KUIoNKJWqnv3 +mn7BR+cI1pxIuXPDH05hDMawEvRr54dZehBAg5IOC0MoDtQu/bupl6DXqwNfZwN7Y7a JQO+LxY3m+sLL7H6ZnPHPAe4KI0YI/z5rEjtlFDY7Mjfpv6CSqqZ6LGDeQvIc6AGvgMm ijZA== X-Gm-Message-State: AGi0PuZXAKJ/SbINIUbzCe6dh+R52JgMROSG0f0STE1oYLNB4kruagn8 XTUTOyz82OSjhyxYktr7tWnkZA== X-Google-Smtp-Source: APiQypKtbeWNjjqucMJ+BC3YWrrXzqesmFdn18zvEh3fztWZsGRRr05NnDcv2TODGa7UTSA8QZCmwg== X-Received: by 2002:a17:902:6114:: with SMTP id t20mr3762825plj.324.1588961760860; Fri, 08 May 2020 11:16:00 -0700 (PDT) Received: from localhost.localdomain (c-73-53-94-119.hsd1.wa.comcast.net. [73.53.94.119]) by smtp.gmail.com with ESMTPSA id e11sm2349463pfl.85.2020.05.08.11.15.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 May 2020 11:16:00 -0700 (PDT) From: Luke Nelson X-Google-Original-From: Luke Nelson To: bpf@vger.kernel.org Subject: [PATCH bpf-next v2 1/3] arm64: insn: Fix two bugs in encoding 32-bit logical immediates Date: Fri, 8 May 2020 11:15:44 -0700 Message-Id: <20200508181547.24783-2-luke.r.nels@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200508181547.24783-1-luke.r.nels@gmail.com> References: <20200508181547.24783-1-luke.r.nels@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200508_111601_836614_ABD4B408 X-CRM114-Status: GOOD ( 16.52 ) X-Spam-Score: -0.1 (/) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-0.1 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:643 listed in] [list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Song Liu , Catalin Marinas , Alexei Starovoitov , Will Deacon , Daniel Borkmann , Marc Zyngier , John Fastabend , clang-built-linux@googlegroups.com, Zi Shen Lim , Yonghong Song , Andrii Nakryiko , Xi Wang , Luke Nelson , Alexios Zavras , KP Singh , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Martin KaFai Lau , Christoffer Dall MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org This patch fixes two issues present in the current function for encoding arm64 logical immediates when using the 32-bit variants of instructions. First, the code does not correctly reject an all-ones 32-bit immediate, and returns an undefined instruction encoding. Second, the code incorrectly rejects some 32-bit immediates that are actually encodable as logical immediates. The root cause is that the code uses a default mask of 64-bit all-ones, even for 32-bit immediates. This causes an issue later on when the default mask is used to fill the top bits of the immediate with ones, shown here: /* * Pattern: 0..01..10..01..1 * * Fill the unused top bits with ones, and check if * the result is a valid immediate (all ones with a * contiguous ranges of zeroes). */ imm |= ~mask; if (!range_of_ones(~imm)) return AARCH64_BREAK_FAULT; To see the problem, consider an immediate of the form 0..01..10..01..1, where the upper 32 bits are zero, such as 0x80000001. The code checks if ~(imm | ~mask) contains a range of ones: the incorrect mask yields 1..10..01..10..0, which fails the check; the correct mask yields 0..01..10..0, which succeeds. The fix for both issues is to generate a correct mask based on the instruction immediate size, and use the mask to check for all-ones, all-zeroes, and values wider than the mask. Currently, arch/arm64/kvm/va_layout.c is the only user of this function, which uses 64-bit immediates and therefore won't trigger these bugs. We tested the new code against llvm-mc with all 1,302 encodable 32-bit logical immediates and all 5,334 encodable 64-bit logical immediates. Fixes: ef3935eeebff ("arm64: insn: Add encoder for bitwise operations using literals") Co-developed-by: Xi Wang Signed-off-by: Xi Wang Signed-off-by: Luke Nelson Reviewed-by: Marc Zyngier Suggested-by: Will Deacon --- arch/arm64/kernel/insn.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c index 4a9e773a177f..cc2f3d901c91 100644 --- a/arch/arm64/kernel/insn.c +++ b/arch/arm64/kernel/insn.c @@ -1535,16 +1535,10 @@ static u32 aarch64_encode_immediate(u64 imm, u32 insn) { unsigned int immr, imms, n, ones, ror, esz, tmp; - u64 mask = ~0UL; - - /* Can't encode full zeroes or full ones */ - if (!imm || !~imm) - return AARCH64_BREAK_FAULT; + u64 mask; switch (variant) { case AARCH64_INSN_VARIANT_32BIT: - if (upper_32_bits(imm)) - return AARCH64_BREAK_FAULT; esz = 32; break; case AARCH64_INSN_VARIANT_64BIT: @@ -1556,6 +1550,12 @@ static u32 aarch64_encode_immediate(u64 imm, return AARCH64_BREAK_FAULT; } + mask = GENMASK(esz - 1, 0); + + /* Can't encode full zeroes, full ones, or value wider than the mask */ + if (!imm || imm == mask || imm & ~mask) + return AARCH64_BREAK_FAULT; + /* * Inverse of Replicate(). Try to spot a repeating pattern * with a pow2 stride.